Conventionally, a post processing device that can be connected to an image forming apparatus main body of a copy machine, a multi-function peripheral and the like has existed. The post processing device performs predetermined post processing on a sheet (or a stack of sheets) having been discharged from the image forming apparatus main body. As the post-processing, punching processing on the sheet, staple processing on the stack of sheets, and processing on the sheet (the stack of sheets) can be exemplified.
The post processing device with a folding function has a blade and a pair of rollers. The blade is brought into contact with a sheet (a stack of sheets) to fold. The pair of rollers pinches and receives the sheet (the stack of sheets) thus folded as well as the blade to thereby make a fold.
Here, in a folding process, the blade may be loaded and damaged with a certain type and number of sheets (stacks of sheets).
In order to address this, an image forming apparatus has been proposed that is provided with a clutch means which drives a pair of rollers to be rotatable in a state in which a blade and a sheet (a stack of sheets) are inserted between the rollers (refer to Patent Document 1).
In addition, an image forming apparatus has been proposed that is configured to be capable of adjusting a crimping force between the rollers in a state in which a blade and a sheet (a stack of sheets) are inserted between the rollers (refer to Patent Document 2).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-184324
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2008-247535